In a semiconductor inspection process, a large number of IC chips formed on a wafer are checked for electrical properties, and those chips which have no defects in electrical properties are screened. The screened non-defective chips are packaged by means of a synthetic resin or ceramic material in an assembly process. In a reliability test, moreover, the packaged products are subjected to temperature stress and electrical stress to detect potential defects and the like in the chips, whereby defective ones can be removed.
With the development of smaller-sized, higher-function electrical products, on the other hand, chips have been reduced in size and enhanced in integration. Recently, various mounting techniques have been developed further to miniaturize semiconductor products. In particular, there have been developed techniques for mounting unpackaged chips or so-called bare chips. The bare chips require quality assurance when they are brought to market. In order to obtain guaranteed bare chips, the individual IC chips must be checked for reliability.
In inspecting bare chips by means of a conventional reliability tester, it is necessary to solve various problems including electrical connections between the bare chips and sockets. Besides, handling the small bare chips is very difficult and possibly entails an increase in inspection cost.
Accordingly, techniques for reliability tests have been proposed in Jpn. Pat. Appln. KOKAI Publications Nos. 7-231019, 8-5666 and 8-340030, for example. According to these techniques, a plurality of wafers can be collectively subjected entire to the tests with IC chips formed thereon.
Conventionally, however, a contactor is opposed to each wafer, contact terminals of the contactor are visually aligned with a plurality of electrodes of a plurality of IC chips formed on the wafer (hereinafter referred to as "alignment"), and the terminals and the electrodes are collectively brought into contact with one another. In carrying out this operation, an operator's operation for alignment between a reference contact terminal and its corresponding electrode pad takes a lot of time. Thus, the operating efficiency is poor, the operator is heavily burdened, and a stable contact state cannot be obtained with ease due to personal errors in alignment accuracy.
In Jpn. Pat. Appln. No. 10-54423, therefore, the applicant hereof proposed a technique (aligner) for forming a unit (hereinafter referred to as "test shell") by translating a stage, carrying thereon a wafer chuck holding a wafer, in X, Y and .theta. directions with respect to a contactor, thereby aligning the wafer and the contactor, moving the stage in a Z direction thereafter, and collectively bringing the three elements, i.e., the contactor, wafer, and wafer holder, into contact with one another by means of a vacuum sucking force that is formed by a vacuum suction mechanism attached to the wafer holder.
This aligner can be also used for the case where the test shell is disassembled or reduced to the aforesaid three elements after testing. During this disassembly, the test shell is transferred from a test chamber to a predetermined position in an alignment chamber. This predetermined position is the same position where the test shell is formed. In disassembling the test shell to the aforesaid three elements, therefore, it is necessary to move the stage accurately to the position where the test shell is formed. By doing this, the test shell and the stage are aligned with each other, whereupon an air charging-exhaust device (valve control mechanism) that is mounted on the stage is connected to a valve mechanism of the vacuum suction mechanism of the wafer chuck. As the valve control mechanism operates the valve mechanism of the wafer chuck, the vacuum sucking force of the wafer chuck is canceled, whereupon the shell is allowed to be disassembled or reduced to the three elements.
Actually, however, the stage cannot always be located in a predetermined position with respect to the test shell that is carried into the alignment chamber after testing. In this case, it is hard accurately to align a valve control mechanism attached to a main chuck with a valve mechanism of the tested shell on the aligner.